Development steps of multimodal exercise interventions for older adults with multimorbidity: A systematic review

Abstract Background and Aims Multicomponent exercise interventions are recommended for older adults and for those with chronic diseases. While multiple programs have been tested, no one has yet explored how these programs were developed. This review set out to determine what development steps multicomponent exercise intervention studies that include older adults with multimorbidity have taken. Methods Systematic review and narrative synthesis. Results One hundred and thirty‐eight studies meeting review criteria (Population: adults ≥60 years with multimorbidity; Intervention: exercise interventions with ≥2 components; Comparator: any considered; Outcome: any considered) were retrieved. Most studies (70%) do not report intervention development actions as suggested by available guidance. Notable deviations from recommendations include limited performance of systematic review of previously published evidence, lack of engagement with theory, and few examples of design then refine. Conclusions Exercise interventions for older adults with multimorbidity do not appear to follow best practice in terms of their developing. Disregard of development recommendations risks contributing to research redundancy and/or avoidable waste, as important steps that make sure the intervention is warranted, suitable for the population in question, and tested using optimal methods and outcome measures are overlooked.

severely impact on quality of life. 7When asked, people with multimorbidity stated their priorities were to prevent social isolation and promote independence. 8To address these priorities, they suggested research should focus on the role of exercise therapy and specifically on establishing efficacy, acceptability, and its effects on important outcomes like isolation, and physical and emotional well-being.
To date, there have been no reviews that have assessed what development steps studies testing exercise interventions in multimorbid older adult populations have taken (i.e., no assessment of how researchers have made important design decisions in relation to their intervention components and the intervention delivery).This review will address this gap in the evidence base, by evaluating study development against expert-derived guidance on complex intervention development.

| RATIONALE AND OBJECTIVES
The range of impacts of multimorbidity, and the priorities set by those who experience it, necessitate the design and testing of complex exercise interventions.In this review, we sought to explore what steps had been taken to develop exercise interventions in studies that involved older adults with multimorbidity and to assess these against current recommendations on the development of complex interventions. 9

| METHODS
We used the Cochrane Handbook for Systematic Reviews of Interventions 10 as a guide for the review conduct and referred to the synthesis without meta-analysis (SWiM) recommendations as an extension to the review conduct. 11In line with best practice, we have followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards for reporting.Ethical approval was not necessary for the conduct of this review.

| Protocol and registrations
The review was deposited in the International Prospective Register of Systematic Reviews (ID: CRD42020209672).

| Eligibility criteria
We included controlled, experimental, quasi-experimental, and pretest post-test studies published in the English language up to November 2020.PICO (Population, Intervention, Comparator, Outcome) criteria are outlined below:

| Population
Studies had to include older adults (≥60 years) 12 with multimorbidity (≥2 multiple health conditions). 1,13We used the definition from The United Nations 12 to define an older adult (i.e., those ≥60 years of age).In studies that targeted older adults and/or one specific condition, we considered multimorbidity to be present if mean comorbidities or mean disease counts were greater ≥2, the Charlson Comorbidity Index score was ≥2, baseline characteristics suggested the sample was multimorbid (e.g., greater than 50% of the sample had 2 or more concurrent conditions).

| Comparison
Any comparisons were considered, including no comparison group, or repeated measure studies.

| Outcomes
All studies and linked reports were assessed against the Framework of Actions for Intervention Development 9 which defines eleven key aspects of complex intervention development.Supporting Information S1: Table 1 described the actions, items considered as part of the action, and a description of the assessment process.Details of the exact search methods can be found in Supporting Information S1: Table 2.

| Study selection
The screening was performed independently in duplicate via the web-based platform Rayyan. 15All full texts that passed initial screening were reviewed by two members of the team; disagreements were resolved by another.All reports related to a study were collated to enable assessment of the development process. 16

| Data collection process and data items
Data items charted included administrative, development assessment, sample details, intervention details, and outcomes.

| Risk of bias in individual studies
Randomized controlled trials (RCTs) were assessed against the Cochrane Collaboration's tool for assessing the risk of bias. 17n-randomized studies were assessed using the Risk Of Bias In Non-randomized Studies of Interventions (ROBINS-I) tool.18 The "mcguinlu/robvis" package was used to generate the risk of bias plots.19

| SYNTHESIS OF RESULTS
In line with best practice, SWiM items 11 have been used to guide the synthesis process and description of the synthesis.

| Grouping, standardization, synthesis methods, certainty
Studies were grouped based on the number and type of exercise components they included and assessed against the 11 consensusdriven complex intervention development actions devised by O'Cathain et al. 9 Studies were also grouped on the basis of the "strength" of their pre-intervention development action whereby a score of ≥3 was considered to represent more robust intervention development processes.We hypothesized that enhanced intervention development processes would be reflected in the number of exercise components as preintervention work would highlight the breadth of impairment in multimorbidity and the need for diverse options to enable participation.
Statistical exploration of the impact on outcome of the number and type of exercise components and the extent of intervention development will be presented in the planned follow-up metaanalysis.Heterogeneity and certainty of evidence will also be considered in this subsequent report.

| Intervention development assessment
An overview of the intervention development assessment results is presented in Figure 2. All studies were perceived to plan the process (A1) in some way.Fewer studies appeared to involve stakeholders (A2).More studies presented evidence suggesting they did bring together a team together (A3).The majority of studies did perform a review of published evidence (A4) in some way.However, studies did not explicitly draw on existing theories (A5) nor articulate program theory (A6).Some studies did undertake primary data collection (A7), however most did not.Within publications, it did seem that studies had taken some steps to understand context (A8), however fewer presented any evidence to suggest actions to attend to future implementation (A9).There was very little evidence to support the concept of design and refine (A10) and an equally high proportion did not end the development phase (A11) in a manner consistent with the guidance.We defined more robust development as "meeting ≥3 development actions"; there was no relationship between a number of exercise components and the robustness of intervention development (Figure 3).
Overall, very few studies provided robust evidence of considering and/or acting upon these important steps when developing their intervention (Figure 4).Most studies (70%) provided no descriptions of actions that were compatible with the complex intervention development framework.Only 19 studies (13.7%) were graded as "yes provided evidence" in three or more developmental action categories.Of these studies, the mean achieved was 5.0 (range: 3-9).Within these studies, planning the process (79.9%), bringing together

| Risk of bias within studies
The risk of bias was assessed using the ROBINS-I 18 and Cochrane Risk of Bias 2 tools (see Supporting Information S1: Figures 1 and 2). 10 Robustness of intervention development did not necessarily translate to methodologically superior studies.Of the 19 developmentally better studies, none were assessed to be of low risk of bias, 16 were graded as presenting "some concerns" (84.2%) and 3 were judged to be at high risk of bias (15.8%).that are not acceptable to the target population. 9Reporting of development activities provides more data and information for future intervention development to be built upon.
In terms of specific intervention development actions taken/not taken, there were a few standout findings.Most studies (86%) were graded as only partly achieving a "review of published evidence" based on the background and rationale presented within the publication.Very few (10.9%) provided emphatic evidence of synthesizing and critically appraising previous literature addressing the same topic via a scoping, systematic, or rapid review.Rather, reports gave the impression of being selective of the studies used to justify their research.This confirmation or optimism bias, especially in the context of a null result, raises doubt regarding the original justification of the research.Authorities on avoidable waste in research have called for the mandating of systematic reviews of existing evidence as part of research funding agreements. 21ly two studies articulated their program theory (a narrative, often diagrammatical, that conveys how an intervention will lead to an outcome) and 12 drew on an existing theory.Evidence that theory use (whether existing or novel) delivers better outcomes in health behavior change interventions is generally lacking. 22However, there are more promising signals for efficacy in exercise trials; 22 particularly in older adults. 23Regardless of their role in changing outcomes, advocates argue theory utilization helps to clarify intervention actions, implementation processes, outcome measures, logistics, and evaluation methods. 24llecting informative "primary" information and "designing and refining" were further development actions that were suboptimally performed.Feasibility or pilot studies allow researchers to test the validity of the research question, design, and methods and they have been shown to reduce research waste. 25[28]

| Application of findings in clinical practice
The impact of these results is most applicable to the research setting.
Given that development guidance has been around for some time (the Medical Research Council framework for complex intervention development first appeared in 2000 29 ); these findings are surprising.In terms of clinical practice, it could be extrapolated that we may not have optimal information to guide exercise prescriptions in multimorbid older adults, as most research reporting to date has not adhered to best practices.

| Comparison with other reviews
We were able to retrieve limited reviews for comparison.A narrative review examining the impact of older adults'; involvement in physical activity intervention development, found all eligible studies (n = 10) reported positive relationships between involvement and outcomes like satisfaction, participation, and adherence. 30

| Limitations of the review process and evidence
This review was large and comprehensive and adopted robust methods that are in line with best practice recommendations.However, there are limitations that must be acknowledged.Firstly, some studies included pre-dated intervention development guidelines, and therefore it may be unfair to judge them against contemporary standards.Second, as other publications have noted, there is a limited appetite within journals to publish "messy" research such as papers that report how an intervention has been developed. 31Third, presence/absence conditions may unfairly penalize studies that have not, for reasons of reporting guidelines and journal requirements, been able to incorporate information relating to intervention design.Fourthly, while assessment criteria and the evidence regarded as satisfying that criteria were established, the judgment is nevertheless, subjective.Lastly, studies published after the search date would have been missed.A search re-run conducted in January 2024 in Medline (via Ovid) identified four studies that would have met our inclusion criteria.These did not report any substantially different patterns of intervention development, so their inclusion would not have materially affected the results as presented.

| CONCLUSIONS
The review has revealed that many exercise interventions tested in multimorbid populations, have not reported intervention design actions in line with current recommendations.Even with equivocal results of efficacy, a well-reported intervention development process can accelerate future work.As such, non-reporting of this process, even when it does not equate to poorly conceived and researched interventions, contributes to avoidable research waste.We have identified important steps in this review, such as reviewing systematic reviews or updating/conducting new reviews, that regularly appear to be overlooked.Further measures should be taken to make sure the intervention design is suitable for, and meets the needs of the population in which it is going to be tested.

A
total of 51,001 papers were retrieved.From these, 138 articles reporting unique interventions were included.We performed extensive searches to retrieve associated texts (e.g., reports of protocols, pilots, and development work) to assess predevelopment/ additional outcomes resulting in a total of 259 articles.The study flow is represented in Figure 1.F I G U R E 1 Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow diagram.

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I G U R E 2 Overview of intervention development assessment.F I G U R E 3 Adherence to ≥3 development criteria and number of components included in the intervention.a team (84.2%), and attending to the future implementation (78.9%) were the most frequently described actions.

6 | DISCUSSION 6 . 1 |
General interpretationThis review found that studies did not frequently report preintervention development work.Although we expect in some cases non-reporting of development activities rather than noncompletion of development activities explain our findings, the results remain concerning.Poor development of interventions increases the risk of testing interventions that are not effective or interventions

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I G U R E 4 Summary of the number of development actions reported.FORSYTH ET AL. | 5 of 7